OST-031: A delicate dance
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- oldeskewltoy
- Posts: 242
- Joined: Thu Jun 20, 2013 10:17 pm
OST-031: A delicate dance
A delicate dance...
titled as such because OST-031 and OST-030 will be built almost simultaneously.
As you can see... OST-030 in the background, with 2 heads in front
Clients head on the left.... anyone see an issue??
How about if we isolate the two sets of chambers.... clients head on top
It's replacement on the bottom
See anything now??
Closer??
I've dismantled the replacement and I've sent it on to get cleaned and pressure checked....
So with it @ the shop to get cleaned, the delicate dance proceeds as I move back to OST-030
More to come...
titled as such because OST-031 and OST-030 will be built almost simultaneously.
As you can see... OST-030 in the background, with 2 heads in front
Clients head on the left.... anyone see an issue??
How about if we isolate the two sets of chambers.... clients head on top
It's replacement on the bottom
See anything now??
Closer??
I've dismantled the replacement and I've sent it on to get cleaned and pressure checked....
So with it @ the shop to get cleaned, the delicate dance proceeds as I move back to OST-030
More to come...
Re: OST-031: A delicate dance
what's the purpose of that chamfer? any idea why that was machined? for larger valves?
- oldeskewltoy
- Posts: 242
- Joined: Thu Jun 20, 2013 10:17 pm
Re: OST-031: A delicate dance
It was machned this way because of poor quality control. In my humble opinion - This head should never have been allowed to leave Toyotaskabrock5 wrote:what's the purpose of that chamfer? any idea why that was machined? for larger valves?
If you look carefully of the 2 panel showing both sets of chambers, the top view shows the middle 2 chambers with similar machining marks (poorly casted) and the chamber on the far right a bit less dramatic, with the chamber on the far left being "normal".
- oldeskewltoy
- Posts: 242
- Joined: Thu Jun 20, 2013 10:17 pm
Re: OST-031: A delicate dance
oldeskewltoy wrote:
So with it @ the shop to get cleaned, the delicate dance proceeds
More to come...
So now that OST-030 is @ the shop getting its valve job, work on OST-031 begins.....
A slightly different angle view on the intake bowls, and chambers... a bit more vertical
This view allows us to see the back of the bowl where it meets the valve seat.
Now when I titled this thread "A delicate dance" originally it was based on working OST-030 side by side with OST-031... BUT OST-031's title has new meaning....
Note how close the gasket edge is to the port outlet roofs... best noticed on end ports, 4 is done, #1 on right is yet to be touched
On #4 (the one done) there was less that .010" to the edge of the gasket. Typically I have over 1/2mm (.0197") or even more!
more to come.......
- oldeskewltoy
- Posts: 242
- Joined: Thu Jun 20, 2013 10:17 pm
Re: OST-031: A delicate dance
from another forum wrote:Don't tell anyone, all gasket manufacturers are the only ones to really know the real speed secrets of every head.
I hear what I BELIEVE you are saying... I only use OEM gaskets when I work the head, because OEM tends to have more consistancy........
I've gotten a bit further since my last post.....
and in more detail.... 2 slightly different views...
1st internally exhaust port #2's transition
and from a slightly different POV...... #3's transition
More to come......
Re: OST-031: A delicate dance
nice, big difference there. incredible how much flashing material is left from factory.
- oldeskewltoy
- Posts: 242
- Joined: Thu Jun 20, 2013 10:17 pm
Re: OST-031: A delicate dance
whoops... sorry I missed this...skabrock5 wrote:nice, big difference there. incredible how much flashing material is left from factory.
yes... and no... remember this is 30 years ago... and it is mass production for profit....
not disputed.... BUT.. the time required/amount of work involved makes it significantly less desirable. Also to consider is the irregularity of the "flaw"s occurance.from another forum wrote:Wouldn't these "bad" heads have better pressure recovery zones?
chamber #1 has no "flaw"... chamber #4 has only a minor "flaw". Do I weld up chambers 1 and 4 and shape them to equal the finished chambers of 2 and 3? My typical finished head goes out the door for under $1500, some under $1000
so... to again answer your question... Yes... these heads would have better pressure recovery, but the work involved makes it less affordable/attractive.
"Pressure Recovery" - is a concept researched by Darren Morgan (Induction Research and Development expert). In essence.....
'pressure recovery' refers to efficient slowing of fluid velocity and transforming the kinetic energy into pressure. In the runner, and especially through a partially-open valve, the velocity is high and the pressure low. In the cylinder, the opposite is true. A gradual transition, as in the exit contour of a carb venturi or through a tapered-hole carb spacer, accomplishes this. Blasting a high-speed air jet into a a big, still cylinder does not.
to simplify this even more(to better visualize)... think of the valve opening inside a funnel.....
- oldeskewltoy
- Posts: 242
- Joined: Thu Jun 20, 2013 10:17 pm
Re: OST-031: A delicate dance
With OST-030 heading back to its owner, and OST-032 at the shop getting cleaned and pressure checked, there is a window of time to check chamber volumes on OST-031, and then re-assemble.
This time I got 35.6 on #1, and #2, #3 was 35.3, and #4 was 35.5
Soooo... I did a little adjustment on chambers 3 and 4 and got both to 35.6
Chamber and bowls... before.... and after
Assembly to follow......
This time I got 35.6 on #1, and #2, #3 was 35.3, and #4 was 35.5
Soooo... I did a little adjustment on chambers 3 and 4 and got both to 35.6
Chamber and bowls... before.... and after
Assembly to follow......
- oldeskewltoy
- Posts: 242
- Joined: Thu Jun 20, 2013 10:17 pm
Re: OST-031: A delicate dance
from another forum wrote:If you had to guess how many hours would you say went into this one?
port work - about 30 hours : chamber deshrouding, and equalizing chamber volumes - 6 hours : waiting for the machine shop to do their thing - 2 weeks
Found another suspect retainer... swapped it out
The head is now ready for its cams.....
More to come.......
- oldeskewltoy
- Posts: 242
- Joined: Thu Jun 20, 2013 10:17 pm
Re: OST-031: A delicate dance
The dance continues.... although now I'm dancing with the valve clearances...
with 13 valves headed back to the machine shop to get tipped...
with 13 valves headed back to the machine shop to get tipped...